1. Astronomy The Original Science

2. Astronomy Astronomy The stars and keeping time The stars and keeping time Calendar Calendar The study of all physical objects beyond the Earth The study of all physical objects beyond the Earth Used since ancient time through observation Used since ancient time through observation A system for organizing time A system for organizing time

3. Year Year Month Month Day Day The time required to for the Earth to orbit the sun once The time required to for the Earth to orbit the sun once Roughly the amount of time required for the moon to orbit the Earth once Roughly the amount of time required for the moon to orbit the Earth once The time required for the Earth to rotate on its axis The time required for the Earth to rotate on its axis

4. Ancient Calendars Ancient Calendars Early Roman Calendar Early Roman Calendar Based on different observations in the sky Based on different observations in the sky Chinese cultures used the moon Hebrew cultures used the moon and sun – their calendars alternated between 12 & 13 months Egyptian cultures used the sun – 12 30 day months and a 5 day month 365 days, 7 day week only 365 days, 7 day week only Started to get out of line with seasons

5. Julian Calendar Julian Calendar Gregorian Calendar Gregorian Calendar It was determined that the year is 365.25 days long It was determined that the year is 365.25 days long Julius Caesar created the leap year Julius Caesar created the leap year Further adjusted the leap year Further adjusted the leap year Length of year is actually 365.242 Length of year is actually 365.242 Should be accurate for another 3,000 years Should be accurate for another 3,000 years

6. Nabta Nabta Stonehenge Stonehenge Earliest astronomical observations Earliest astronomical observations 6,000-7,000 years old 6,000-7,000 years old Egypt Egypt Lined up with Summer Solstice Lined up with Summer Solstice Salisbury, England Salisbury, England Lines up with many movements of the sun Lines up with many movements of the sun Built from 3,000 B.C. to 1,500 B.C. Built from 3,000 B.C. to 1,500 B.C.

7. Babylonians Babylonians Ancient Chinese Ancient Chinese Ancient Greeks Ancient Greeks Precisely tracked positions of planets and moon Precisely tracked positions of planets and moon 700 B.C. – 50 A.D. 700 B.C. – 50 A.D. 1000 B.C. could predict eclipses 1000 B.C. could predict eclipses Named 800 stars by 350 B.C. Named 800 stars by 350 B.C. Used math to understand our place in the solar system Used math to understand our place in the solar system Aristotle Aristotle

8. Native Americans Native Americans Ancient Arabs Ancient Arabs Maya Maya Complex systems of math and astronomy Complex systems of math and astronomy Buildings aligned with astronomical events Buildings aligned with astronomical events Invented algebra Invented algebra Inherited the Greeks’ knowledge during Dark Ages Inherited the Greeks’ knowledge during Dark Ages